Sussex to double capacity at Inland Bays treatment plant

Sussex County officials are taking the first steps to double capacity at the Inland Bays regional wastewater facility near Long Neck. They also hope to eliminate weather-related issues that can limit spray irrigation at the two Cape Region treatment plants.

Average treatment at the Inland Bays facility is 1 million gallons per day. “If we do nothing with the projected growth by 2027 it will reach its 2-million-gallon-per-day limit,” said Hans Medlarz, the county's chief engineer.

With the growth threatening to push the county's Wolfe Neck regional wastewater facility to capacity, Medlarz said it's prudent to work toward a goal capacity of 4 million gallons per day at the Inland Bays plant.

There is no room to expand the Wolfe Neck plant, which borders Cape Henlopen State Park. The Wolfe Neck plant treats about 2 million gallons of wastewater per day with a capacity of 3 million gallons per day. But, the facility only has 310 acres of land to use for spray irrigation. The plant has been cited two times in 20 years for illegal effluent runoff by state environmental officials.

A new pump station along Route 1 near Lewes now under construction would allow wastewater flow to be directed to either the Wolfe Neck or Inland Bays plants. The $5 million pump station is the only one of its kind in the Sussex County system.

Included with that is a $7 million project to add a 24-inch, 10-mile-long transmission line from the pump station to the Inland Bays plant.

In addition, Medlarz said, the engineering staff is investigating what to do when the weather – particularly long, wet or cold spells in the winter and spring – prevent spray irrigation, particularly at the Wolfe Neck plant. During some of those rainy periods, wastewater must be stored in lagoons and not sprayed on the plant's fields.

He said seasonal capacity is available at other locations that do not utilize spray irrigation.

Sussex officials are considering a collaboration with Lewes Board of Public Works, private companies and the City of Rehoboth Beach to accept wastewater during their nonpeak periods.

Medlarz said Lewes has significantly lower usage in the winter and spring months and could possibly handle some of the flow that would normally go the Wolfe Neck plant with the addition of a new transmission line.

Lewes treats its wastewater and discharges into the Lewes-Rehoboth Canal.

“It's a possible concept, and we are ready to take it to the next level,” Medlarz said.

The county is in the process of expanding its spray irrigation area at the Inland Bays plant including wooded and agricultural sections. Twenty-five-year-old irrigation rigs are also being updated. “We'll have almost unlimited summer spray irrigation capacity,” Medlarz said.

The Inland Bays facility covers about 2,000 acres with 430 acres of irrigated crop land. The expansion project would add another 300 acres in a wooded area of the property.

Phase 2 of the Inland Bays expansion project is soon expected to get into high gear. At its July 17 meeting, county council approved a $408,000 contract with Whitman, Requardt & Associates for the design of the expanded spray irrigation project for up to 4 million gallons per day.

In addition to all of the planned capacity/flow work, county officials have also approved the construction of a regional septage facility that would eventually be open to private septage haulers. When that facility opens, the county will no longer accept septage at its South Coastal treatment plant near Bethany Beach.

Total cost of the upgrades at the Inland Bays facility will be about $35 million, Medlarz said. “We are turning a page,” Medlarz said.

Most of the funding for the projects comes from previously collected sewer connection charges, Medlarz said. The project will take about four years to complete.

The county operates four wastewater treatment facilities: Wolfe Neck between Lewes and Rehoboth Beach; Inland Bays near Long Neck; South Coastal near Bethany Beach; and Piney Neck near Dagsboro.

Three of the four plants use a lagoon system and then spray irrigation to dispose of wastewater while South Coastal has used ocean outfall since 1976. A 6,200-foot, 30-inch pipe pumps treated water out into the Atlantic Ocean. The Town of Selbyville has also tied into the South Coastal system.